Hydraulically-operated shovel



W FERRIS Feb. 17, 1931.

HYDRAULI CALLY OPERATED SHOVEL File-dose. so, .1927 5 Sheets-Sheet 1 K kw O o INVEN TU)? M hzrm f5" EH15.-

I/f 1 1 14 A TTURNEY Feb. 17, 1931. w. FE RRIS 1,793,438

HYDRAULICALLY OPERATED SHOVEL Filed Dec. 30/1927 5 Sheets-Sheet 2 INT/EN TUE I V IL TEE FEE/P15.

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w. FERRIS Feb. 17, 1931.

HYDRAULICALLY OPERATED SHOVEL 5 Sheets-$heet 4 Fild Dec.

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Feb. 17, 1931. w. FERRIS HYDRAULICALLY OPERATED SHOVEL Filed Dec. 30, 1927 5 Sheet s-Sheet 5 I N V EN TOR. W4 L TE)? FZWRJE A ATTORNEY.

an improved hydraulic drive 2 sure.

Patented Feb. 17, 1931 UNITED STATES PATENT OFFICE WALTER FERRIS, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO BUC'YRUS COMPANY, OF SOUTH MILWAUKEE, WISCONSIN, A OORIPORATION OF WISCONSIN HY'DRAULICALLY-OPERAT'ED SHOVEL 5 shovel of a well known type.

A general aim of the present invention is to improve the power efiiciency in machines of the character mentioned.

A more specific object is the rovision of or effecting the several characteristic motions involved in the operation of such machines without requiring the use of throttle valves here-' tofore employed 'for controlling and regulating those motions. Throttle valves are a direct cause of power waste particularly in machines of the type mentioned" wherein the load condition is a continuously and widely varying factor. Assume, for example, that it is necessary to maintain a pressure of 400 pounds at the pressure source in order to elfect operation of the hoist motor under full load, but that that motor at half load requires only a 200 pound working pres- When operating at half load'under throttle valve control the difference in these pressures is wasted by the frictional resistance offered by the throttle valve, so that as much power is actually consumed dur ing half load operation as is required for full load operation. In my copending application, Serial No. 243,738, filed December 30, 1927, I have described a hydraulic system for machines of the character mentioned in I which throttle valves are eliminated. In

r gulated by regulating pl lmp displacement.

The present invention provides a-hydraulic drive of a type quite different from that described in said application and possessing certain advantages thereover. In it each of the several motions are effected by a variable stroke motor, whose capacity or torque be varied to accommodate the variable load. O

Another specific object of. the present invention is the provision of a hydraulic drive of the character mentioned so designed that the prime mover need be only of such capacity as to carry the average load. In all mechanical drives heretofore used in machines ofthe type referred to the load reacts directly on the prime mover, so that it is necessary that the prime mover be of sufficient capacity to carry the maximum peak loads. This is also true of electric drives heretofore I used and of the, hydraulic drive described in the above entitled application, and in the throttle valve controlled hydraulic drives heretofore employed the prime mover is always working under maximum load. By the use of the present invention it is possible therefore to employ a prime mover of smaller capacity than is required in the various forms of drives heretofore designed.

Another object of the present invention is the provision of a hydraulic drive wherein the power, ordinarily lost by the use of. brakes in this class ofmachines, may be returned to the system and thus rendered available to assist the prime moverin carrying the load.

.Other objects and advantages will appear from the following description of an illustrative embodiment of the present invention.

In the drawings:

Figure 1 is afragmentary plan view of a revolving type power shovel equipped with vention. I

Fig. 2 is a fragmentary side, elevation. Fig. 3 is a sectional view taken substantially along the line 33,0f Figure 1.

Fig. 4 is a sectional view of one of the sev- I eral variable stroke 1 and 2.

Fig. 5 is a diagram of the hydraulic system.

motors shown in Figures Fig. 6 is aside view r 'a modifid form of hoist mechanism mounted on the boom.

Figs. 7 8, 9 an'd'10 are sectional views of a control valve illustrating three characteristic positions thereof.

The power shovel shown in Figures land 2 is of a well known type. It includes a truck frame 10, mounted upon appropriate creeping traction mechanism 11, and carryingthe usual circular rack and track member 12. It also includes the usual revolving platform 13 supported in the usual manner upon rollers 14 disposed to travel upon the member 12. A pinion l5 fixed to a vertical shaft 16, journaled in the platform 13, meshes with the member 12 and coacts therewith to swing the platform about a vertical axis. A boom, which is attached at its lower end 17 to the platform, carries the usual dipper, such as that shown in Fig. 6. The dipper is operated through the usual hoist cable 18 from a drum 19 on the platform, the thrusting or crowding of the dipper being effected through the usual shipper shaft, such as that shown in Fig. 6, carried by the boom and actuated through an endless chain 20.

In this instance three separate hydraulic motors 21, 21', and 21" are provided for op erating the swing mechanism, the hoist mechanism, and the thrust mechanism, re-' spectively. Each is a variable torque motor of a well-known type and in this instance is structurally similar to the variable displacement pump which is fully described in my prior Patent No. 1,558,002, issued October 20, 1925. Each includes a substantially circular cage 22 (see Fig. 4), mounted for rotation about a fixed axis in a housing 23, and directly connected to a driven shaft 24, 24 or 24". A cylinder barrel 25 is disposed within the cage 22 and rotatably supported upon a pintle 26 which is laterally adjustable to vary the eccentricity between the cage and barrel. The cylinder barrel contains a series of radial bores 27, each having a port 28 adapted for communication successively with ports29 and 30 formed in the pintle during rotation of the barrel thereon. Port 29 communicates with an upper pair of longitudinal passages 31 formed in the pintle and port 30 with a lower-pair of similar passages 32. Each bore 27 contains a piston 33 having a cross-head 34 for coaction with aseries of tangential reaction plates 35 removably fixed in the cage22. A n antifriction bearing 36 transmits the pressure between each crosshead and reaction plate. The pintle 26 is i carried by an upright arm 37 rockably supported upon a shaft 38 fixed in the housing and containing two pairs of laterally spaced longitudinal passages 39 and 40. The arm 37 contains a passage 41 connecting passages 39 with pintle passages 31 and a passage 42 connecting passages with pintle passages 32 Passages '39 are supplied with liquid under pressure through a pipe 43, 43' or 43" and passages 40 discharge through a pipe 44, 44' or 44". The arrangement is such that with'the pintle and cylinder barrel in the eccentric position shown in Figure. 4, the outward thrust ofthose pistons iLbOWB the pintle, under the pressure of liquid transmitted through the upper pintle port 29, causes the cage 22 to rotate counter-clockwise, and during this rotation the pistons below the pintle are forced inwardly by the reaction plates 35 so that liquid is discharged through the lower pintle port-30 into the passages 32. It will be noted that the torque of the motor is pr 0- portional to the degree of eccentricity between the "cylinder barrel 25 and cage 22, the torque being zero when these members are concentric and maximum at maximum eccentricity. Thus by adjusting the arm 37 the torque or capacity of the motor may be varied at will. In this instance the position of the arm is controlled by a plunger 45 which in turn is controlled by a rock shaft 46, 46, or 46 having arack-and-pinion connection 47 therewith.

Motor 21 drives the shaft 24, which carries a pinion 48 in mesh with a gear 49. Gear 49 drives a bevel gear 50 which meshes with a bevel gear 51 carried by the shaft 16 hereinabove mentioned. Motor 21 drives the shaft 24 which in turn drives the hoisting drum 19, through appropriate gearing 52, and the traction mechanism, through gearing conventionally shown at 53. Motor 21" drives the shaft 24" which carries a drive sprocket 54 for the chain 20 constituting a priate high pressure reservoir 57 mounted 'at the rear end of the platform 13, and pipe 56 leads to a low pressure reservoir 58, similarly situated. Both pipes 55 and 56 are equipped with appropriate cut-off valves 59 and 60 which are open except when the machine is not in use. The torque or capacity of each motor is separately controlled through appropriate means such as individual levers 61, '61, and 61" connected to the separate rock shafts 46, 46 and 46", respectively, through appropriate linkage 62, 62, and 62".

The high pressure reservoir shown comprises an upright cylindrical tank 57 of rather large capacity which in normal operation is partially filled with liquid, 'preferably oil, exposed to the pressure of a body of compressed air trapped within the upper end thereof. The air is supplied preferably from the reservoir.58 through a pipe 63 in a manner to be hereinafter described and the liquid is supplied from a pump 64 through pipes 65 and 66. Any appropriate means such as a vertical series of pet cocks 67 may 'be used to ascertain at any time the true level of the liquid in the tank 57, and a gauge 68 indicates the pressure therein. The low pressure reservoir shown also comprises an upright cylindrical tank 58 of somewhat less capacity, but which, in normal operation is also partially filled with liquid exposed to the pressure of a body of air trapped within the upper end of the tank. The tank 58 is provided with a check-'valve-controlled air inlet 69 and a check-valve-controlled air outlet 7 O communicating with the'pipe 63. Liquid is initially -,supplie'd to the tank 58 through a pipe 71 from the pipe 65. A glass gauge 72 indicates the liquid level and a gauge 73 indicates the pressure within the tank 58.

Athird tank74, also mounted at the rear end of the platform 13, forms a liquid storage reservoir. Pipes 75 and 76, controlled by valves 77 and 78, permit drainage of the tanks 57 and 58, respectively, into the tank 74. A pipe 79 leading from the bottom of the tank 74 supplies liquid to a pipe 80 leading to the pump 64, and a. pipe 81 leading from the bottom of the tank 58 is nectable to the pipe 80.

A three way valve 82 of a well known type is adjustable to connect pipe 80 with pipe 79 or 81, selectively. This valve includes a rotary plu having a diametral passage 83 through w ich pipe 80 is connected with pipe 81 when the plug is in the position of Figure 5, and having a radial passage 84 communicating with passage 83 to effect communication between pipes 80 and 79 when the plug is rotated clockwise through a 90 degree angle from the position shown in Fig ure 5. A similar valve 85 is adjustable to connect pipe with pipe 66 or 71, selectively. It also includes a plug having a diametral passage 86 for connecting pipes 65 and 66 when in the position shown in Figure 5 and a communicating radial passage 87 through which pipe 65 is connected with pipe 71 when the plug is rotated clockwise through a 90 degree angle from the position shown. The valves are controlled by appropriate hand levers 88 and 89. I

The pump 64 is a reversible flow variable displacement pump of a well known type. That shown is fully described in the copending application of Walter Ferris and John P. Ferris, Serial No. 92,135, filed March 4,

1926. It will therefore suflice here to state v that this pump is driven at constant speed through a drive shaft 91 and that the displacement thereof is variable from zero to a maximum in either direction byadjustment of a lever 92. It thus receives liquid through pipe 80 and discharges liquid also con '71 into the bottom of the tank 58.

above mentioned a further or more detailed description thereof is deemed unnecessary. In this instance the pump is driven by an appropriate prime mover, such as a gasoline engine 93, directly coupled to the shaft 91.

In preparing the s stem for operation the tank 57 is first supplied with compressed air and thereafter it is supplied with liquid, preferably oil, pumped thereinto against the pressure of the entrapped air until the liquid has reached a desired level, such as that indicated in Figure 5. The compressed air is supplied preferably in the following manner. Both; of the valves 59 and 60, as well as the drain valves 77 and 78, are closed, and the valves 82 and 85 are so set that pipe 79 coma municates with pipe 80 and pipe 65 with pipe 71; The engine 93 is then started to operate the pump 64, and the coritrol handle 92 of the pump is so set that the pump draws liquid from the tank 74, through pipes 79 and 80, and discharges the same through pipes 65 and The liquid thus forced into the tank 58 drives air therefrom through the check valve and pipe 63 into the tank 57 When the air from the tank 58 is thus completely expelled, the control handle 92 is shifted so as to reverse the pump and thereby cause the pump to Withdraw the liquid from the tank 58 and return the same to the tank 74. During this latter operation check valve 70 closes to retain the air in the tank 57, and check valve 69 opens to again admit atmospheric air to the'tank 58. This process is repeated until the desired air pressure ordinarily about 250 pounds has been established in the tank 57. Liquid is there-.

after pumped into the tank 58, in the manner just described until a relatively low pressure of about 50 pounds has been established therein. -Valve 85 is then adjusted so as to-open communication between pipes 65 and 66 and thereby direct the discharge from pump 64 into the lower end of tank 57 against the pressure of the air previously forced thereinto. This continues until the air cushion has been compressed to the desired working pressure, ordinarily about 350 pounds, at which pressure the unloading mechanism embodied in the pump responds automatically toreduce pump displacement. At this pressure the liquid ordinarily assumes a level" approximating that indicated in Figure 5. Valves 59 and 60 are then opened and valve 82 adjusted to connect pipe 81 with pipe 80. The several motors 21, 21 and 21" are thus exposed to the high pressure in tank 57 through pipes 55, 43,43 and 43", and to the low pressure in tank 58 through pipes 56, 44, 44, and

44 and the machine is ready for operation. Durlng operation the valves 82 and 85 remain in the positions shown in Figure 5 and the 'control handle 92 of the pump ordinarily remains set in such position as to cause the pump to receive liquid from the low pressure reservoir 58 through pipes 81 and 80 and to discharge liquid in the high pressure reservoir 57 through pipes and 66, but the rate of flow through the pump is controlled by the pressure within the high pressure reservoir due to the automatic action of the unloading mechanism, hereinabove mentioned, constituting a part of the pump. So long as the pressure in the reservoir is below the average working pressure (ordinarily 350 pounds) pump displacement, and hence the rate of flow, corresponds to the setting of the handle 92, but at pressures abovethis working pressure pump displacement automatically reduces and actually approaches zero at pressures greatly in excess of the average working pressure.

It will be noted that in the hydraulic system hereinabove described the low pressure tank 58 performs two distinct functions. In preparing the high pressure reservoir for operation it serves as an air pumping medium, thereby eliminating the necessity for a costly multi-stage air compressor for the purpose, and during operation of the system it serves to prevent accumulation of air within the system by maintaining a pressure above atmospheric pressure throughout the piping thereof.

Provision is also made for collecting leakage from the several motors and pump and for returning to the system sufficient liquid to compensate for leakage. To this end the leakage trapped within the several housings of the motors and pump is returned to the tank 74 through a system of drainage pipes 95, and a small gear pump 96 of a well known type is employed which draws liquid from the tank 74 through pipes 79 and 97 and delivers the same into the low pressure tank 58 through a pipe 98. The discharge pressure of the gear pump 96 is controlled by a pres sure relief valve 99 connected in the pipe line 98, and a check valve 100 within the pipe line 98 prevents the escape of liquid from the tank when serving its auxiliary capacity as an air pump for the high pressure reservoir. The discharge from the relief valve 99 may be directed into the drainage system 95 through a pipe 101.

A brief description of the operation of the system will now be given. Let it be assumed that the control levers 61, 61 and 61" of the several motors 21, 21' and 21. are all in intermediate position so that the cylinder barrel 25 of each is concentric with its cooperating cage 22 and so that the torque of each is zero in spite of the diiference in hydraulic pressures within the upper and lower pintle passages. To hoist the dipper it -is only necessary to shift the control lever 61 x in one direction to thereby shift the cylinder barrel of motor 21 into eccentric relation with the cage, and thus so increase the torque of that motor as to cause the same to drive the hoisting drum against the load 'of the dipper thereon. During that operation the motor is actuated by liquid supplied from the high pressure reservoir 57 through pipes 55 and 43 and returns liquid to the low pressure reservoir 58 through pipes 44 and 56. Then to lower the dipper the torque of the motor 21 is reduced until'it is less than that necessary to sustain the dipper load, the motor reverses its motion, and, acting as a pump under the dipper load, discharges back into the high pressure pipe 55, and by this power regenerating process actually saves the power heretofore wasted by the braking methods ordinarily used. The dipper thrusting action is similarly regulated and controlled by manipulation of the control lever 61 of the motor 21 and the platform 13 may be swung in either direction by manipulation of the control lever 61 of the motor 21 in one direction or the other from the intermediate position.

It will be noted that the pump 64 is operated continuously throughout the operation of the machine to thereby maintain a supply of high pressure liquid within the high pressure reservoir 57 The capacity of the high pressure reservoir and the quantity of compressed air therein prevents an undue reduction in the pressure during peak load conditions so that the pump and prime mover 93 need be only of sufficient capacity to carry the average load.

The hoist mechanism shown in figure 6 includes a motor cylinder 105 mounted on the boom 17 and cooperating with a piston 106 reciprocable therein. A piston rod 107 projecting from the upper end of the cylinder 105 carries a sheave 108. A similar sheave 109 is mounted on the lower end of the cylinder. The dipper 110 is supported by a cable 111 which in this instance is trained about the sheaves 108 and 109 and is anchored at one end 112 at an appropriate point on the boom. The arrangement is such that the dipper is elevated by outward travel of the piston'106 within the cylinder 105, and that the weight of the dipper reacts through the cable to urge the piston downwardly. It will be noted that the volumetric capacity of the upper end of the cylinder 105 is reduced by the presence of the rod 107 therein so that the effective cross-sectional area thereof is less than the effective cross-sectional area of the such as thehigh pressure'reservoir hereinabove described, leads to one side of an appropriate control valve 114. A discharge pipe 115 leading from the opposite side of form chambers 118 and 119, each adapted for communication with any of the pipes 113, 115, 116 or 117. The chambers are separated by an intermediate partition 120 containing a diametral passage 121 which communicates with chamber 118 through a passage 122. The passage 121 lies in the plane of the pipes 116 and 117 so that it may register therewith, but the pipes 113 and 115 are below the plane of this passage.

The arrangement is such that with the valve in the position shown in Figure 7 all four pipes are blocked and the dipper remains at rest. To elevate the dipper the Valve is adj usted into the position shown in Figure 8 in which position pressure pipe 113 communicates with pipe 116 and discharge pipe 115 with pipe 117 so that the lower end of the cylinder is exposed to the pressure source and the upper end is free to discharge through .the pipe 115. To lower the dipper from an upper position the valve is shifted into the position shown in Figure 9, in which position the discharge pipe 115 is blocked and the pressure pipe 113- is open to both pipes 116 and 117 through the passages 122 and-121. Both ends of the cylinder are thus exposed to pressure. When in an upper position the weight of the dipper isv suflicient to overcome the greater total pressure in the'lower end of the cylinder, so that the dipper lowers and the piston travels downwardly in the cylinder. The Volume of liquid discharged from the lower end of the cylinder is greater than that admitted to the upper end thereof during this action and the excess passes back through pipe 113 to the high pressure reservoir to thereby partially replenish the liquid taken therefrom during the hoisting operation. During lowering the weight of the dipper is utilized to regenerate power in the pressure source as in the form of hoistin .mechanism first above described. I. To permit the dipper to swing freely the valve is shifted into the position shown in Figure 10 in which position the pressure pipe 113 is blocked and the discharge pipe 115 is open to both pipes 116 and 117 through passages 122 andv 121. When pipe 115 is'open to a low pressure reservoir the pressure maintained therein keeps the cylinder and piping full 'of liquid when the valve is in the position last mentioned.

Various changes may be made in the embodiment of the invention hereinabove spe-. cifically described without departing from or sacrificing the advantages of the invention as defined in the appended claims.

I claim:

1. In a machine of the character described the combination of a prime mover, a hoist mechanism, a swing mechanism, a thrust mechanism, a hydraulic pressure source, a variable displacement pump driven by said prime mover and having its displacement responsive to the pressure at said source for maintaining a working pressure therein, and three variable capacity hydraulic motors driven from said source for operating said mechanisms respectively.

2. In a machine of the character described the combination of a hydraulic pressure source, a hoist mechanism, a variable capacity motor connected with said pressure source, driving connections betweensaid motor and said hoist mechanism, and means for increasing the capacity of said motor to thereby operate said hoist mechanism by liquid sv-pplied from said pressure source and for decreasing the capacity of said motor to a degree insuflicient to sustain the load imposed thereon by said hoist mechanism and thereby return liquid to said pressure source by the reaction of said hoist mechanism motor. c

8. In a machine of the character described the combination of a hydraulic pressure source, a variable displacement pump having on said its displacement responsive to the pressure atsaid source for maintaining a workingv pressure therein, a hoist mechanism, variable capacity means hydraulically connected with said pressure source for operating said hoist mechanism, and means for increasing the ca pacity of said means to thereby operate said hoist mechanism by liquid supplied from said pressure source and for decreasing the capacity of said means to a degree insufficient to sustain the load imposed thereon by said hoist mechanism and thereby return liquid to said pressure source by the reaction of said hoist mechanism on said means.

4. In a machine of the character described, the combination of a hoist mechanism, a swing mechanism, a thrust mechanism, a hydraulic pressure reservoir, a variable displacement pump for supplying liquid to said reservoir, means for driving said pump at substantially constant speed, the displace-' ment of said pump responding to the pressure in said reservoir to control the rate of supply of liquid to said reservoir, three variable cap'acaity motors driven from said reservo1r for operating said mechanism, respectively, and means for regulating the capacity variable capacity hydraulic motor for driving said swing mechanism, a thrust mechanism, a separate variable-capacity hydraulic motor for driving said thrust mechanism, apressure reservoir for supplying driving liquid to said motors, a substantially constant speed prime mover, and a. variable displacement pump driven by said prime mover for supplying liquid to said reservoir, the disolacement of said pump being responsive to the pressure in said reservoir to thereby automatically regulate the supply of liquid thereto, and individual means for regulating the capacity of said .notors to thereby regulate said mechanisms individually.

6. In a machine of the character described, the combination of a hoist mechanism, a variable capacity hydraulic motor for driving the same, a swing mechanism, a separate variable capacity hydraulic motor for driving said swing mechanism, a thrust mechanism,.a separate variable capacity hydraulic motor for driving said thrust mechanism, a pressure reservoir for supplying driving liquid to said motors, an internal combustion engine, a variable displacement pump driven by said engine for supplying liquid to said reservoir, the displacement of said pump responding to the pressure in said reservoir to automatically regulate the supply of liquid thereto, and individual means for regulating the capacity of said motors to thereby regulate said mechanisms individually.

7. Ina machine of the character described, the combination of a swing mechanism, a variable capacity hydraulic motor for driving the same, a thrust mechanism, a separate variable capacity hydraulic motor for driving said thrust mechanism, a pressure reservoir for supplying driving liquid to said m0- tors, an internal combustion engine, a variable displacement pump driven by said engine for supplying liquid to said reservoir, the displacement of said pump responding to the pressure in said reservoir to automatically regulate the supply of liquid thereto, and individual means for regulating the capacity of said motors to thereby regulate the operation-of said mechanisms individually. 7

8. In a machine of the character described the combination of a hoist mechanism, a

hydraulic motor for driving the same, a swing mechanism, a separate hydraulic motor for driving said swing mechanism, a thrust mechanism, a separate hydraulic mo tor for driving said thrust mechanism, a pressure reservoir for supplying drivlng liquid to said motors, a constant speed prime mover, a variable delivery pump driven by said prime mover for supplying liquid to said reservoir, the rate of delivery of said pump responding to the pressure in said reservoir to automatically regulate the supply of liquid thereto, and individual means for regulating the operation of said separate motors to thereby regulate the operation of said mechanisms individually.

9. In a machine of the character described the combination of a swing mechanism, a hydraulic motor for driving the same, a thrust mechanism, a separate hydraulic motor for driving said thrust mechanism, a pressure reservoir for supplying driving liquid to said motors, a constant speed prime mover, a variable delivery pump driven from said prime mover for supplying liquid to said reservoir, the rate of delivery from said pump responding to the pressure in said reservoir to automatically regulate the supply of liquid thereto, and individual means for separately regulating the operation of said motors to thereby regulate the operation of said mechanisms individually.

In witness whereof, I hereunto subscribe my name this 28th day of December, 1927.

WALTER FERRIS. 

